The purpose of this study was to assess how an investigational drug, cilansetron, alters symptoms of patients with irritable bowel syndrome, how it changes the speed with which food and residue move through different regions of the digestive tract, and how it changes feelings within the rectum. This is a multi-center study in which Mayo is participating; however, a single center portion of the study will be conducted only at Mayo which was investigator initiated. This study is completed. The national visibility of our group in the context of irritable bowel syndrome trials and motility disorders in general was enhanced by our participation. Our contribution to the multicenter trial will eventually result in a publication, and we anticipate being critically involved in the analysis of the multicenter trial data and publication.